Texas Bay and Estuary Study Program

1. WMHS 602 February 8, 2006 Texas Bay and Estuary Study Program Cindy Loeffler, Chief Water Resources Branch

2. Freshwater Inflows… Salinity Nutrients …By Definition Create and Sustain Estuaries Sediments

3. The Fundamental Scientific Basis of the Studies The Fundamental Goal of the Recommendations TWC Section 11.147 Defines Beneficial Inflows As the “Salinity, Nutrient, and Sediment Loading Regime Adequate to Maintain an Ecologically Sound Environment in the Receiving Bay and Estuary System That Is Necessary for the Maintenance and Productivity of Economically Important and Ecologically Characteristic Sport or Commercial Fish and Shellfish Species and Estuarine Life Upon Which Such Fish and Shellfish Are Dependent.”

4. Objectives & Constraints Verification Nutrient Analysis Hydrology Hydrographic Survey Fisheries Needs Analysis Sediment Analysis Fisheries Regression Analysis TxBLEND Habitat Analysis TxEMP Optimization Model FWI Recommendations Hydrodynamic & Conservation Transport Model The Process of Developing FWI Recommendations

5. FWI Recommendations Are Based on the Biological Needs of a Group of Target Species Expressed As A Statistical Relationship Between Harvest or Catch per Unit Effort And Inflow Target Species: Blue Crab Eastern Oyster Red Drum Black Drum Spotted Sea- Trout Brown Shrimp White Shrimp H = 110.64 – 145.3*ln(Qjf) + 332.5*ln(Qja) – 141.4*ln(Qso) H = 3000.7 + 180.4*ln(Qma) – 963.3*ln(Qmj) + 710*ln(Qja) - 231.5*ln(Qso) H = 32.786 + 0.0797*Qmj + 0.2750*Qja – 0.2010*Qnd H = -18.087 + 0.2411*Qjf – 0.1734*Qma + 0.0850*Qnd ln(H) = 2.6915 – 0.7185*ln(Qma) + 1.86*ln(Qmj) – 1.086*ln(Qnd) ln(H) = 6.5679 + 0.6707*ln(Qja) – 0.7486*ln(Qso) H = 545.59 + 160.9*ln(Qjf) + 279.1*ln(Qmj) – 155.1*ln(Qja) - 277.9*ln(Qnd)

6. TPWD and TWDB Have Jointly Developed FWI Recommendations To Maintain the Health and Productivity of Texas Estuaries TxEMP Is The Optimization Model That Produces a Range Of Inflows Within Which Estuarine Health and Productivity Needs May be Met

7. A Range Of Possible Solutions Lies Between Two Points Along An Optimization Curve: MaxQ and MinQ MaxH is FWI Necessary To Sustain Historic Fisheries Harvest as Evaluated Against Existing Fisheries Data To Meet The Legislative Definition Of Beneficial Inflows MinQ Is the Minimum Inflow That Maintains 80% Of Mean Historic Harvest and All Other Physical Constraints: Salinity, Nutrient, and Sediment Needs

8. Delivery of Freshwater Inflows Must Incorporate Seasonality to Have Any Ecological Significance FWI Seasonal Distribution San Antonio Bay The Recommended FWI Is Often Expressed As a Single Annualized Number, But Always Infers The Sum of Bi-Monthly Inflows

9. Identify and Assemble Datasets Representative of Estuarine Ecosystem Identify and Assemble Datasets That Reflect Changes in Inflows FWI Recommendations Summary: Methodology to Determine the Freshwater Inflows Necessary to Meet the Legislative Directive of TWC Section 11.147 Input Real Data Into Models And Assess Projected Estuarine Conditions Create Models That Integrate Datasets and Predict Response To Varying Freshwater Inflows

10. Sabine 9.5* Galveston 5.2 Matagorda 2.0 San Antonio 1.15 Aransas 0.82 Nueces 0.14 Laguna Madre 0.25 Legislatively Mandated Studies to Determine “Beneficial Inflows” Necessary to Conserve Health and Productivity Of Texas Major Estuaries Have Been Completed. Some are Being Updated. * Millions of Acre Feet Per Year

11. Case Study Galveston Bay

12. TxEMP MinQ and MaxH Solutions

13. TxEMP Monthly Flow Distribution

14. TXBLEND Output • Monthly Salinity Maps Under Each TxEMP Solution • Salinity Difference Maps • Spatial Relationships of Modeled Salinity Zones to Critical Habitat Areas

15. White Shrimp Abundance in Galveston Bay • Higher abundance correlates with lower salinity levels

16. Galveston Bay TXBLEND Time Series • Daily salinity at a point in Upper Galveston Bay • Predicted salinity within upper and lower limits for MaxH and MinQ

17. TxEMP MinQ and MaxH Solutions TPWD Recommendation

19. Comparison of Model Solutions to Historical Inflows

20. Reviews Methods for Determining Minimum Freshwater Inflow Needs of Texas Bays and Estuaries - Powell, Matsmuto, Brock. In Estuaries December 2002. “Nowhere in the World Has the Issue of Freshwater Inflow Been Studied So Systematically, or The Results Used to Guide Water Management Policies and Practices So Effectively, Than in the State of Texas.” – A Review and Application of Literature Concerning Freshwater Flow Management in Riverine Estuaries (2000), by Dr. E. Estevez, Director, Center for Coastal and Tropical Ecology, Mote Marine Laboratory, Sarasota, Florida.

21. Reviews “While the State of Texas has pioneered tools to address freshwater inflow needs for bays and estuaries, there are limitations to these tools in light of both scientific and public policy evolution.” – Science Advisory Committee to the Study Commission on Water for Environmental Flows, Interim Report to the 79th Legislature, December 2004

22. Summary of SAC B&E comments • Incorporate stakeholder input/peer review • Commercial vs. independent fisheries data • Improve statistical methods • TPWD “Verification” analysis • Optimum inflow vs. drought conditions • Adaptive management and precautionary principle methods